The Pyrenees offers great scenery for a family on a walking holiday Photograph: Madeleine Bunting

Planning a family holiday in our household is rather like a 70s-style union/management meeting. It requires subtle, discreet negotiating with key potential allies to outmanoeuvre the opposition and achieve that elusive goal: not just grudging but enthusiastic agreement on where to go.

This may sound far fetched to anyone with children under 10, but as soon as they tip into their teens, the family holiday becomes an exercise ground for adolescent assertiveness. Be warned: it starts with those delightful conversations you have with your seven-year-old in which you say such things as, "Don't you think it'll be wonderful to go camping in France?" For a few years, they agree to whatever you suggest. But then they come up with ideas of their own. And you find your wily negotiating strategies fail in the face of a dogged opposition.

Back in February there was general agreement on two points: no one wanted to fly anywhere and no one wanted crowds. But after that came some tough non-negotiables: a teenage daughter (Eleanor) who refused to go anywhere hot, wanted to be near water and, more importantly, insisted we take the family dog (Sanna) - her preference was the west coast of Scotland. A 12-year-old son (Luke) who wanted adventure (preferably mountains), and his seven-year-old brother (Matthias) whose capacity and appetite for exercise is limited.

Walking in the Pyrenees met with instant approval from eldest son and husband. I fondly imagined the family, packs on their backs, trekking from refuge to refuge among the high peaks; a notion which perhaps owed more than I wanted to admit to the final scenes of The Sound of Music. But the daughter flatly refused. Not Spain. It's hot. Look at the snow, I responded. But to no avail.

It was Brittany Ferries which kept the negotiations on track. Their ferry to Santander takes dogs and would land us on a beautiful coast, where the climate is relatively mild for Spain. The dog plus a few days on the beach before and after the walking might overcome Eleanor's objection. She reluctantly agreed.

There then followed a lot of internet surfing and several telephone conversations in broken Spanish as I tried to find out how dog-friendly Spain was likely to be. Many of the house rental companies and hotels won't allow them in high season, likewise the Pyrenean refuges. Finally, we found a house in a tiny village in the middle of nowhere where my protestations that our dog is "muy educado" seemed to satisfy the owner, and booked it for a week. The rest of the time we would take our chances with camping, as most of the sites seemed to accept dogs.

The verdict? Taking Sanna was an unmitigated disaster. We were lulled into a false sense of complacency by the efficiency of the ferry's canine provision. The kennels were a little grim but there was plenty of space for exercise and Eleanor spent most of the 24-hour journey on the rain-sodden deck. In the meantime, everyone else enjoyed the smoothest way to travel, easily beating tedious, long car journeys or crowded airports. While the children watched a film in the cinema, we snatched precious time reading and lingering over Breton pastries.

At Camping Las Arenas, a wonderful campsite on the Cantabria coast, an hour west of Santander, we discovered the first hitch. We had failed to notice intimidating signs forbidding dogs from the beach. For the first day we obeyed and then noticing that no one else did, we put Sanna on a lead and took her with us. But whether it was the journey, or the other campers - at the not particularly crowded site - or the unfamiliar crash of surf, there was a lot of barking to contend with, quite apart from a wet, sandy dog sleeping sprawled across much of the tent. Doubts were beginning to form.

Madeleine Bunting and her daughter during the family's walking holiday in the Pyrenees Photograph: Madeleine Bunting

The first day in the Pyrenees, in a village which exceeded even our hopes for remoteness - the shops were a winding 45-minute drive down the mountain - hiking boots were on for what I promised would be a short walk: just two hours to a nearby abandoned village. Four hours later we limped home, exhausted; I'd misread the guide book. But while our limping was only temporary, the dog's was not. She was in agony and could barely stagger out to pee. She had burnt the pads of her paws, and it took several days for her to resume anything like her usual exuberance.

Neither did she like the heat. A black Labrador who revels in damp walks on northern British moors, she was baffled by the Spanish sun. She wilted indoors for most of the rest of the holiday. Her coup de grace was to vomit in the car all over Eleanor's legs on the journey home. Perhaps that was her verdict on a holiday which must have seemed like a series of torture experiments (including a much hated visit to a Spanish vet as required by British regulations). Even my daughter had to concede that bringing the dog had not been a great success.

But the main purpose of the holiday was walking in the Pyrenees, and despite the disappointment of losing Sanna's company, that can be marked down as a triumph. Of sorts. It may have seemed odd to ignore the Picos de Europa, just an hour from Santander, and drive five hours further, but the near blanket of cloud was a helpful reminder of a previous holiday when we glimpsed the peaks just once in a fortnight.

Working out a day's walk for a family is rather like a Sudoku puzzle. Kids set clear requirements: the first was water. If I could plot a walk which included a river for a swim, that was a great spur for tired legs. Then, the route had to be short enough to be manageable for a seven-year-old, with not too much sun for shade-loving Eleanor. Luke was itching to climb a peak, but anything too steep prompted vetoes from the other two children.

Most of our hiking was in and around the Valle de Vió near the hamlet of Buerba in the Alto Aragon where we were staying. We were just outside the Parque Nacional de Ordesa so could still see the magnificent peaks of this famous park, but didn't have to contend with the crowds of walkers or the strict regulations, which include a meticulously observed ban on swimming. (It's painful after a long hot walk to resist the temptation of a delicious pool of clear water.)

Instead, we found plunge pools which we had to ourselves in the nearby river Yesa; screened by cliffs, they were perfect for a skinny dip and sunbathing on the big flat rocks. We explored wooded hillsides, ravines and gorges without seeing a soul. Every step prompted flurries of brilliantly coloured butterflies around our legs, while high above our heads we watched eagles and vultures through binoculars as they soared the thermals.

There were plenty of footpaths, well marked with small but prominent flashes of paint every few hundred metres. It was all very reassuring. When you are walking with children, you cannot afford to get lost; nothing saps their morale and strength more quickly. Most of the villages marked as abandoned (there is a lot of restoration into holiday homes going on), still have the old fountains or springs to refill water bottles. But there were no pit stops for ice lollies so rucksacks were packed with treats needed to maintain energy levels.

It's a poignant landscape full of reminders of the remote mountain agriculture which is no longer practised. Terraces were crumbling, abandoned fields full of blue harebells and the creamy flowers of umbellifers. One day, we sheltered from the sun in the dark of a collapsing chapel, eating our lunch in the company of a colony of bats while cicadas rattled outside in the long grass of the abandoned graveyard.

But within a few days, my reputation as a map reader had gone beyond redeemable. On too many occasions my promises of a short walk, shade, flat contours, or a river for swimming, had all proved false. In my defence, I point out that the standard walkers' map for the area gave little indication of contours nor when rivers dried out in the summer. One short distance on the map turned out to be a climb up the near sheer side of the spectacular gorge d'Anisclo. There was a bold attempt to reach one particularly romantic crumbling village which had to be abandoned - the children flatly refused to walk any further.

But the biggest misjudgment of all was a walk in the national park. The entrance to the Valle de Ordesa is by coach from the nearby village of Torla - and the coaches don't take dogs. So one party had to set off in advance and walk an extra hour and half into the park with the dog (now back in health). I then blithely promised a lovely stroll through some alpine meadows. Seven hours later, after a walk up the dramatic valley into the scree covered corries of the Pyrenees, we staggered back to the campsite. I promptly collapsed with hypoglycemia and lay shivering fully dressed in a sleeping bag, while the children revived sufficiently to round the day off with a game of badminton.

Despite occasional protests, even my seven-year-old had comfortably exceeded my strength. Perhaps it was the sight of so many Spanish and French families with children as young as five, all dressed in proper walking boots, striding effortlessly up the mountain, which spurred my brood on.

When I watched my eldest son awestruck by the huge eagles soaring above him, or saw my daughter bounding down the mountain after an eight-hour walk, or my seven-year-old's sturdy legs, I reckoned we'd cut a great deal. They'd imposed some conditions which proved awkward but we'd ended up with something that still resembled our idea of a holiday. The 12-year-old's only disappointment was that he didn't reach the summit of a peak but he's already thinking of walking the Pyrenees in his gap year; his brother is planning to hang a framed picture in his room, showing him at the foot of a Pyrenees' peak; his sense of achievement is immense. And my daughter says despite the heat, she loved the holiday, but also reminds me of her side of the deal we struck: next year it's Scotland.

Way to go

Getting thereBrittany Ferries (0871 244 1400, brittany ferries.com) offer returns from Portsmouth or Plymouth to Santander for a family of four, with car, from £598. Kennel for dog from £66 rtn.